Loudspeaker and method of formation



April 16, 1940. R NEUSCHOTZ .2,'197;649

LOUDSPEAKER AND METHOD OF FORMATION Filed NOV. 14, 1936.

g? 3 2 3 L 2 I Patented Apr. 16, 1940 UNITED STATES PATENT orrrce LOUDSPEAKER AND lVIET'HOD OF FORMA- TION Application November 14, 1936, Serial No. 119,791

2 Claims.

This invention relates to sound reproducers, and particularly to sound reproducers of the loudspeaker type in which a magnet structure provides an air gap for a voice coil connected to the sound emitting diaphragm.

The object of the invention is to provide a loudspeaker in which the magnetic structure and the diaphragm support are simply and efiiciently combined for ease of manufacture and accuracy in assembly, maintaining the parts in precise alinement and permanently operative so as to be durable in use.

A further object of the invention is to provide a system for the alinement and assembly of parts which will automatically give proper relative positioning and maintain the vibratory elements accurately centered in position with relation to the remaining structure.

In the accompanying drawing illustrating the invention:

Fig. 1 is a sectional view of one form of loudspeaker,

Fig. 2 is a sectional View illustrating the system of assembly of portions of the loudspeaker structure.

In the specific embodiment of the invention illustrated in the drawing, a basket or chassis l of generally spider type circular formation is provided with a peripherally flanged portion 30, to which is cemented radially extending flange 1 of the vibratory diaphragm or cone 2, a felt-paper ring 3 being cemented to the face of the flange I so that in installed position of the speaker the flange T is separated from the supporting panel by this ring 3. The center of the cone 2 is reversely conical as shown at 3|, providing a central plunger portion having an annular apex 32, to

which is fastened the voice coil cylinder 8 carrying the voice coil V. The basket or chassis I is provided with an annular shoulder ill, to which is cemented the outer edge of a centering net 4 formed of stiffened gauze-like fabric corrugated to give it additional axial flexibility and preferably water resistant or repellent, and the inner edge of this centering net is cemented at 9 to the outer surface of the cone 2 a short distance outward of the apex 32.

A magnet assembly 5 consists of a back plate H, a pole piece I2, magnet casting l3 and front plate M grouped together as shown and fastened together by screws l5 passing through the front plate M and threaded into the back plate I! in such relationship that an air gap G is provided between the surfaceof the hole in the front plate 14 and the front end of the pole piece l2. In this (01. ire-415.5)

way air gap G is positioned around the voice coil V carried by the voice coil cylinder 8, and it is of great importance precisely and accurately to position this voice coil in the air gap and maintain the alinement throughout the life of the= speaker.

The chassis I has a constricted neck portion l6 providing the opposite shoulders l0 and I8 and beyond the shoulder I8 is the flange l1 fitting closely around the outer edge of the end plate M, which is so designed that its central hole is accurately concentric with this outer edge, and the outer edge in turn is adapted to slide into the angular circular collar formed by flange l1 and shoulder 18 until the magnet edge comes to rest against the shoulder I8. By this construction the magnet parts on the one hand and the chassis and sound diaphragm on the other are adapted for assembly as separate units and are then brought together with precise alinement of the voice coil V and the air gap G, when as in the system of this invention the voice coil V is initially assembled in accurate concentricity with the flange I7.

Referring to Fig. 2 illustrating the assembly 01 the basket or chassis and vibratory parts, a mandrel or form 29 is provided and has a precisely concentric core 2|, the outer surface of the mandrel being accurately machined to just fit within the flange I! while the core 2| similarly fits within the voice coil cylinder 8. Before assembly on this mandrel, the chassis I has the centering net 4 cemented to the shoulder Hi to relatively fix these parts with relation to each other. The diaphragm or cone 2 is laid loosely in place with unset cement between these parts so that this outer flange I is slidable on the peripheral portion 30 of the chassis and so that the entire diaphragm is adapted to shift in response to the movement required to permit the voice coil cylinder 8 to center itself on the core 2|. Similarly the cement between the centering net 4 and the diaphragm at the point 9 is unset and permits relative shifting between these parts. Then when these structures are accurately positioned, as indicated in Fig. 2, the weight ring 23 is positioned carefully in place as shown bearing down slightly to depress the diaphragm to force the voice coil further down on the core 2! and to hold all of the parts snugly in place while the cement at point 9 and the flange 30 is setting. The feltpaper ring 3 is added after the insertion of the weight ring 23 and is cemented to the outer surface of the flange 1 of the cone 2, the entire assembly being set aside to dry. The upwardly extending ring portion 22 of the mold 20 holds the centering net so as to maintain it in firm contact with the diaphragm during this setting period.

After the assembly of the parts of the chassis and diaphragm and the setting of the cement, the chassis unit is assembled on the magnet unit by bringing these parts into axial alinement and moving the voice coil V into the air gap G as the flange I! fits over the edge of the end plate I4, securing means, as for example a grip ring l9, being provided to fasten these parts together by spanning the flange IT and engaging under the overhanging edge of the front plate It as shown. This grip ring is drawn tight by nut, bolt, rivet, or other tensioning or holding means between two flanges 6 at the extremities of the I claim:

1. A loudspeaker comprising a magnet unit in- Or the 7 cluding a core and end plate forming an annular air gap and having a peripheral surface accu rately concentric with said air gap and a rearwardly facing ledge on said peripheral surface, a chassis unit including a vibratory diaphragm carrying a voice coil in position in said air gap and including a basket frame supporting said diaphragm and having a constricted circular neck and an angular circular collar beyond the neck, the collar having a flange fitting the periphery of the magnet unit and a shoulder engaging the end of the magnet unit to center the voice coil in the air gap, and a grip ring hav-- ing a rear flange engaging said rearwardly facing ledge of said magnet unit and a front flange positioned over and engaging the angular circular collar of the basket frame with said. grip ring under circumferential tension all around to fir.- ly grip and support the magnet unit from the chassis unit with the voice coil accurately centered in the air gap.

phragm centering dewrice.

ROBERT 1 r.E.'|::rs :::-zo'I'z 

